Method of preventing froth on paper machines



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S T .PATENTA OFFICE" tar'msoN -"A nu criw; or Mo'oiv'r vnnnom unw YORK, ,assienon To rnocnss ENGI- Nunns, mo or new YORK, 1v. Y., A conroRArIoN on NEW YORK.

' No Drawing.

Paper .Machines aspecification.

I have'dis'covered that the formation of 10 ,injurious frothon the screens of paper ma: chines is due-to two causes, namely,.agitation of the stock inthe presence of air, and the capacity -of the stock to form froth due to v .the'presence in'the stock of certain frothing agents.

, mation of excessive froth; When such froth is formed is found to contain alot of pulp fibres,= which have been carried in the films of the froth bubbles. These fibres are held in the froth by certain oils which may be foundcin smallquantities either in sul phate. orfsulphite pulp, 01" in mill waters ."containing the Waste liquors from the manufacture of, these p'ulps, or. the rosin used in making the size'may contain a trace of these flotation oils. 2 1 These-oils cause Be it known" that I, Jonson A. DE Claw, f a citizen of the Dominion of Canada, residing at Mount Vernon, New York, have in;

5 vented certain. new and useful Improvements in Method'spf Preventing Froth on of which the following Application filed December 14, 1921 Serial No. 522,341.

, will be suflicient.

products. 1

enou h to cover others.

METHOD OF rnnvnurme morn 0N rerun morrmns.

precipitate the size with aluminum sulphate (alum), forming aluminum 'resinate, and then addthe ferrous sulphate to the stock j to destroy the tendency ofthe pulp to adhere '.to the froth. The amount used'will vary with the amount of froth but as general practice, from two to ten pounds per beater More mlght be used if re- 5 I I quiredjwithout injury to the stock but it is not desirable to use an excess, especially in lighter colored papers.'-

lVhen treated in this manner, no iron resinates are formed, the/sizing is not injured and the dangerous froth is not formed,

7 V This treatment is especially adaptable to Both conditions are necessary to the for- .kraft paper and other unblea h P5 1 6 1 Thereare other chemical agents that have a destructive action on the flotation property so while ferrous sulphateis my preferred one, I consider my invention broad ile" I have herein referred to the prevention of injurious froth I do not mean to say that absolutely no froth will be formed :but that what froth may be formed will be of such a nature that the fibreswill not adhere thereto and therefore will not be floated the' froth and this does theidamagejon the thereby. Accordingly, my invention conpaper machihe. I

' I have also discovered means for preventing the formation'of this injurious froth. One means/ is to add to the paperstoclz', q certain agents which eith'eralter' the surfacetension conditions or cause some other e'fiect ivhich destroys the flotation properties of the'oily impurities. I ff ,These means 'are'thatt cl l products. which willdes'troy'the" flotation 0 properties in the fibres, and is represented b'y'ferrou's'sulphate (FeSO This material is known to the trade as oopperas or green crystals, and has been used in paper:- making as a substitute for alum 1n sizing 45 the paper, but with poor success because 1 ironresinates have very: little sizing value.

-My method of-using it however, is to'first c nating in the What I claimis:

s of chemical ble iron salt.

Juns

- sists,essentially in the prevention of the formation of injurious froth but is broad enough to cover the conversion of injurious A froth into a non-injurious kind by 'elimireviously described manner l 'the aflinity of t e froth for the fibres.

. 1. Amethod 'of decreasing the frothing properties of a paper pulp which has been treated with rosin size and alum, which consists in precipitatingsoluble frothing ingre- ;dients by means of a treatment with a solu- 2. The method of claim 1, using ferrous 9 In testimony whereof I have afiixed my signature to this specification.

ONA.DE onw. 

